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June 19, 2014 (NEW YORK) -- A single injection of Botox, which is typically used to improve the appearance of facial wrinkles, may be an effective treatment for depression.

Investigators at the Hannover Medical School in Germany found that treating the facial muscles involved in emotion with Botox eases symptoms of depression.

"Our emotions are expressed by facial muscles, which in turn send feedback signals to the brain to reinforce those emotions. Treating facial muscles with botulinum toxin interrupts this cycle," study investigator Prof. Tillmann Kruger said at a press conference at the American Psychiatric Association's 2014 Annual Meeting.

Novel Approach

According to the investigators, positive effects on mood have been seen in patients who've had Botox treatment for the frown lines in the area above the nose and between the eyebrows. To confirm these results, Kruger and colleague M. Axel Wollmer, MD, from the Asklepios Clinic North Ochsenzoll in Hamburg, Germany, did research on Botox injection as an additional treatment for major depression.

A total of 30 patients with high levels of chronic and treatment-resistant depression were enrolled in the study. Patients were randomly assigned to receive a single injection of Botox or a single injection of saline placebo ("fake treatment").

Six weeks after a single treatment, the Botox group had an average 47.1% reduction in depression symptoms vs. 9.2% in the placebo group.

The investigators found that the effect size was even larger at the end of the study. Improvement was also reflected when other tools were used to measure depression symptoms.

Kruger said Botox may offer a "novel, effective, well-accepted, and economic therapeutic tool for the treatment of major depression."

These findings have since been repeated in two other studies.

The researchers are also testing Botox’s therapeutic potential in other psychiatric disorders.

Jeffrey Borenstein, MD, president and CEO of the Brain and Behavior Research Foundation in New York City, said at the press conference that pursuing new treatments for depression is "crucial."

Borenstein said he'd like to see this line of research pursued in studies that include larger numbers of patients.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.